The effect and mechanism of dexamethasone on apoptosis of blood eosinophil in vitro

Objective To study the effect of glucocorticoid on apoptosis of eosinophil in vitro. Methods Eosinophils were incubated in vitro in the presence of different concentrations of dexamethasone with interleukine 5 (IL 5), with the presence of IL 5 alone as a positive control and medium alone as a negative control. The changes of eosinophil apoptosis were assessed by trypan blue exclusion and in situ tailing techniques and the expression of bcl 2 protein were also observed in the same time. Results IL 5 inhibited the apoptosis of eosinophils in vitro and increased the expression of bcl 2 significantly ( P 0.01). Dexamethasone antagonized IL 5 mediated eosinophil survival in a dose dependent and time dependent manner Dexamethasone at 10 -6 mol/L inhibited significantly eosinophil survival caused by IL 5 (1×10 4 U/L) and decreased the expression of bcl 2 Conclusion Dexamethasone can inhibit IL 5 mediated eosinophil survival and expression of bcl 2, which may be an important mechanism for dexamthasone to induce apoptosis of eosinophil